FR2487283A2 - Variable length bicycle crank - has sliding sections under control of guide chains and maintained at equal lengths - Google Patents

Abstract

The pedal cranks (5) can have their length varied by sliding via two flexible connections (7,8) fixed to the crank ends (5,5A) and passing along their length. They cross inside the hollow shaft (4). The crank and shaft are held perpendicular in two blocks (1,1A). One of the has fixing lugs (3) for an exterior sprocket. The flexible connections are chains and their equal tension ensures equal length of the cranks. Shortened cranks enable pedal power to be used when riding around sharp curves with the bicycle inclined accordingly.

Description

 The present invention relates to pedals allowing, instead of two opposite and linked cranks, to make a rotary movement.

 In known devices of this kind, the cranks are rigid branches which, on a bicycle impose a single circular trajectory on the legs of the user and which prevent the latter from maintaining his driving thrust during the inclination when cornering.

The crankset according to the invention allows, by its variation in length, a more complete use. On the one hand, by the change in gear resulting from this process, on the other hand by the possibility of maintaining and increasing the speed of a bicycle in rapid turns with high inclination. The equal change in length of the two pedals is due to its repercussion between the two cranks by two cables or chain crossing the axis and keeping an equal tension whatever the mobile position.

 As shown, the device comprises casings I, IA provided with covers 2.2A. The assembly IA, 2A comprises in its external volume the legs 3 of the transmission pinion. The covers 2 held by three screws on the casings I enclose and immobilize the hollow axis 4 whose curved, cut or keyed ends allow blocking. Also take place in the housings I two cranks 5 and 5A whose play allows a sliding in length, blocked at the ends of their length. In the present case, the cranks 5 have on their central face a trench 6 whose role is to house the cables 7 or chain two in number transmuting a movement of equal length from one crank to the other, 7 and 8 in place on the cranks 5.5A crossing in axis 4 passing on curves 9 to right angle. The shape being the same symmetrically on both sides, the push of a crank has the effect of an equal displacement of the other, however, a balanced pedaling movement must be able to allow a stable rotation. The time required to master the device is one of the peculiarities of its playfulness.

 The device which is the subject of the invention can be used on all standard types of bicycles and on objects provided with lines of axial symmetry.

 Presentation of the drawings.

Figure I shows the assembled object, halfway through. Figure 2
is a flat view in half section; The cranks are then at the end
race. Figure 3 shows a perspective of the housing I in isolation.

Claims (1)

 CLAIM  Crankset with variable length cranks held securely by two flexible links (7,8) fixed to the ends of the cranks (;, 5A), crossing the length of those criss-cross and crossing inside the hollow axis (4. The cranks and the lever are held perpendicularly in two blocks (I, 2 and IA, 2A). One of the two blocks has the fixing lugs of an external transmission plate.